89 XJ 4.0 run and die

[comancheon33]

I just picked up an 89 XJ limited 4.0 auto and a NP242. I had to fix a few vaccuum leaks and needs a valve cover gasket bad. Now the problem is it runs and dies. With no spark has plenty of fuel. I havent checked for injector pulse yet. I am guessing it is a bad or unproperly adjusted CPS. Maybe a possible ignition module. Hoping that I am headed in the right direction, or someone else has any ideas. Help me if you can Thanks in advance.

 

[8Mud]

In 17-18 years of Xj´s, I´ve never replaced an ignition module, but there was a recall on one batch, guess it´s possible.
My experiences with CPS, is most times they won´t start. Once (if) they start, they run OK.
How long does it run before it dies?

 

[comancheon33]

it varies ran 20 mins one time then 5 mins 2hours later. This morning wouldn't start at all. I need to check for injector pulse to be positive. Then I wouldn't hesitate about the CPS. There is a TSB on alldata that says to check for possible to far out of range condtion. Says it needs slotted CPS mount to correct it. I dunno for sure.

 

[afd516]

My experiences with CPS, is most times they won´t start. Once (if) they start, they run OK.

Granted, my expierince was rare but my CPS was missing a bolt which caused it to be off kilter. It would still read the crank and start and run but it would not rev up over 1200 rpm. It would spit and spatter the little bit that it would rev over that but would not die when you let off the gas. :wierd:

Like I said unusual but non the less it took me a month to figure it out. I put the bolt back and took offroad with no issues since.

CPS crankshaft positioning sensor? Are we talking about the same thing?

 

[comancheon33]

I had that same problem in my 91 MJ. It da only one really loose bolt in it. Had the exact syptoms you had. It really messed with me for a short awhile.
Mine had actually rubbed on the flywheel a little. That was 6 months ago and it still works.

 

[DrMoab]

Its an off chance but...I had my jeep start and die...Would only run as long as I was holding the key on. Ended up being that I knocked my ballast resistor wire off while changing my aircleaner...If that was going bad....Who knows. Might be worth looking at though.

 

[8Mud]

I just replaced the CPS in my 89, the no starts, were getting more frequent, day by day. Did notice after I replaced the CPS, it did run a little different. The CPS tested good for ohms and AC pulse. Started up a few days (week) after a motor wash, maybe some oil got into yours.
I used a piece of tubing to listen for injector clack while cranking, didn´t hear any (but my starter is really loud), on a hunch changed the CPS, seems to have done the trick.
Did notice on the ohm test it was at the edge of the allowable tolerance, which is 200 ohms +/- 75, mine was 245 Ohms, motor hot.

 

[wilcharl]

an intermitnent die if it was the CPS would sound like the CPS wire melting on the exhaust manifold and grounding out.... from there i would go to the shake and rattle technique.... the ground between the firewall and the engine block will kill a renix in a heartbeat and mine would go 5 or six miles, it would jiggle and die.... knowing the ol'e renix system im gonna say its an electrical issue and the intermitentness is from shake rattle and rolling

 

[8Mud]

an intermitnent die if it was the CPS would sound like the CPS wire melting on the exhaust manifold and grounding out.... from there i would go to the shake and rattle technique.... the ground between the firewall and the engine block will kill a renix in a heartbeat and mine would go 5 or six miles, it would jiggle and die.... knowing the ol'e renix system im gonna say its an electrical issue and the intermitentness is from shake rattle and rolling

Sounds good to me, the CPU grounds on the dipstick holder, the ground wire (on mine) was soldered to the ground ring, the TCU ring wasn´t and corroded where the wire went in. There is/was a notice to change the order of the ground stack at the dipstick holder. When I cleaned the block to firewall ground (paint under the ground ring) there was a noticeable change in the way the motor ran. I added a ground from the dipstick holder to the firewall and from battery ground to the front clip and soldered the ground ring bundle together, with the extra ground to the firewall, just as a little insurance. The area around the dipstick holder is kind of an oil active area, for more reasons than one. I wanted a little insurance.
If you do an ohm check on the CPS, try it in various flex plate positions , the resistance changes (due to the notches/cutouts). They say to check it, with the motor at operating temperature, if it won´t start, thats hard. Mine seems to also have a resistance change with the temperature. CPS ohm check seems kind of iffy, guess that´s why it´s plus or minus 75 ohms.
I had both the cooked CPS wire and a fatigued wire in the injector harness where it makes the bend at the firewall (in my old 87). The fatiuged wire was under the bundle and the single wire insulation, took me a while to find that one.
I had a loose connector on my MAP that would periodically stop me in my tracks.
I rerouted the CPS wire (up with the speedo cable) and put a section of platic shielding on it. It was laying in a loop, on top of the bell housing/tranny, the loop just kind of flopped around up there, then ran up next to the manifold.

 

[Nevada City Sparky]

Access to CPS

OK, since this is a common problem, I too have a CPS on order to fix my intermittent non-starts.

QUESTION: I scoped out the location of the CPS. How the hell do you get in there? I didn't jack it up, but when I got under there to feel where the bolts were, it was pretty damn tight. Any tips on the technique, other than using a universal socket.

 

[8Mud]

Find somebody with really small hands, good group project for the girlfriend or wife. Seriously, a stack of extensions, ours was a good 18" long with a universal on the end. Somebody with a flashlight, can kind of talk you onto the bolt heads from the top, while you try to find them from the bottom. It looked like after disconnecting the MAP vacuum line, the fuel line, other odds and ends and pushing the harness up, I could get my big old hands in there from the top, wasn´t happening.
On a pain in the rear scale of 1-10, I´d rate it a 6 or 7. If you have trouble starting bolts, from odd positions, it´s a 7-8.

 

[clayman]

I had a problem with my 94 XJ dying randomly. Sometimes 5 min into the drive sometimes 2 hours later. Sometimes after it died I would have some trouble starting it up again, but usually it would start right back up. Anyways I replaced the CPS (about 1 month ago) and haven't had any problems since. I don't know much about the differences between a 94 and 89 but your problem sounded similar.

Also I also used stack of extensions and a universal on the end to get the CPS out of there. Also, do the top bolt first. I've heard of people dropping that bolt down in the tranny and being alot of trouble to get it out. It was pretty easy to do for me but I have a 2wd so there isn't as much stuff in the way.

 

[Nevada City Sparky]

Find somebody with really small hands, good group project for the girlfriend or wife. Seriously, a stack of extensions, ours was a good 18" long with a universal on the end. Somebody with a flashlight, can kind of talk you onto the bolt heads from the top, while you try to find them from the bottom. It looked like after disconnecting the MAP vacuum line, the fuel line, other odds and ends and pushing the harness up, I could get my big old hands in there from the top, wasn´t happening.
On a pain in the rear scale of 1-10, I´d rate it a 6 or 7. If you have trouble starting bolts, from odd positions, it´s a 7-8.

Thanx 8Mud, that's exactly how it was lookin' to me. Didn't seem like any easy way from the top or bottom. I could get a socket on the lower bolt, but that top one looks like a braille experience. Now, to find a midget mechanic.......

 

[wilcharl]

Ive had the CPS out more then once best word of advise is coat the bolts in a really thick greese and the socket ... it will hold them in place while your lineing them up.... makes it heck alot easier and the last thing is u dont wnana drop one of those bad boys down inside your tranny

 

[comancheon33]

Thanks for help guys. I found a bad connection at the plug for CPS. Seemed to fix it. We will have to see what happens.